SINGAPORE, Dec 3 (Reuters) - Top Philippine oil refiner Petron Corp exported a diesel cargo in November in a rare move, and offered a December-loading shipment, trade sources said on Monday.

Petron sold a November-loading diesel cargo with 50 parts-per-million (ppm) sulphur for export, the first time in several years, they said.

The cargo was sold to Unipec, the trading arm of China's state-owned refiner Sinopec, one of the sources said.

Last week, Petron also offered a 50ppm sulphur diesel cargo for loading over Dec. 17 to 19 from Bataan, the source added. It was not immediately clear if that tender has been awarded.

Petron could not be immediately reached for comment on the matter.

The Philippines is typically a net importer of diesel and it is not usual for the country to export diesel, traders said.

With Asian diesel refining margins spiking to a four-year high in mid-November, refiners in the region have been maximising output of the oil product which is typically used in the transport, agriculture and industrial sectors.

"Refineries are running high, so they likely had extra cargoes to export," a second source said.

Asian diesel margin subsequently plunged to below $14 a barrel to Dubai crude, its lowest in more than four months on Friday, before recovering to nearly $15 a barrel on Monday, Refinitiv Eikon data showed.